This invention relates to a collapsible bicycle frame, and, more particularly, to a bicycle frame which includes a rigid main frame and a rear frame which is pivotally connected to the front frame and movable between riding and storage positions.
Various types of collapsible or folding bicycles have been proposed in the past. However, many of these bicycles are constructed in a way that makes it difficult and time-consuming to change the bicycle from its riding position to its collapsed or folded position. Further, with the increasing popularity of multiple speed gear mechanisms, e.g., five speed and ten speed mechanisms, it is desirable that the bicycle can be moved between the riding and collapsed positions without interfering with the gear mechanism.
A bicycle constructed in accordance with the invention can be easily and quickly moved between the riding and collapsed positions. The bicycle includes a non-collapsing, rigid main frame which can be made as strong as desired. The collapsible rear frame includes a first pair of struts which are pivotally connected to the bottom of the main frame. The ends of the struts are provided with slots for receiving the axle of the rear wheel, and the gear mechanism is mounted on one of the struts. A second pair of struts is pivotally connected to the ends of the struts of the first pair, and when the rear frame is in its riding position the struts of the second pair extend forwardly and upwardly and are releasably connected to the upper rear of the main frame. When the rear frame is to be folded, the rear wheel is removed from between the struts, the upper ends of the struts of the second pair are disconnected from the main frame, and both pairs of struts are pivoted forwardly until the upper ends of the struts of the second pair can be connected to the upper front of the frame. Lever-operated quick-connect-disconnect connecting members are mounted on the main frame at the front and rear thereof for connecting the struts of the second pair to the frame in the folded and riding positions, respectively, and the rear connecting member is also used to clamp the seat to the main frame. The struts of the first pair are pivotally connected to the frame adjacent the center of the pedal sprocket, and the distance between the gear mechanism and the pedal sprocket remains substantially constant as the rear frame is pivoted so that the chain can be maintained in position around the pedal sprocket and the gear mechanism as the rear frame moves between its riding and folded positions. The only connection that must be made to maintain the rear frame in either position is at the ends of the struts of the second pair.